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The Winter Mouse Invasion

By Chris Williams on December 18, 2011.

Q. Why do I have more mice in the Winter and what should I do about it?

A. When outside temperatures fall mice need to find a warm place to stay, and your home provides the perfect location. Mice are warm blooded mammals, and need to keep warm. Due to their small size and weight (typically around 1oz.), hypothermia sets in rapidly outside. Without a safe, warm nest site mice will quickly die as body temperatures fall. Wood piles, holes in the soil, stored power equipment, cars and clutter provide adequate shelter, but no heat. Eventually all the good places to shelter outside become uninhabitable. Mice are able to enter very small holes. Holes as small as the tip of the human pinky finger will allow mice entry to warm spaces within your home. Some common entry points include corners(especially homes with vinyl siding), gaps at the sides of the front steps, oil filler pipes, AC lines, roofline trim, chimney flashing, gaps at the roofline including where the chimney goes into the soffit, garage door frames and weather-stripping. In most cases sealing the obvious openings is not that hard. “Great Stuff” foam, caulking, trim pieces, and flashing are ideal solutions for this task.

Other hard to reach areas like the ridge vent, missing siding, large holes and unfinished exterior gaps( a finished door inside the bulkhead is a must!!) may require the attention of a contractor or wildlife specialist. Pest Control operators generally rely on the use of baits placed in specific locations to knock down the mouse population. Traps may be used to speed the initial kill and locate dead rodents. Whenever rodenticides are used there is the possibility of dead mice in walls or other locations, and the ensuing odor. Once a mouse dies, the fluid within the mouse begin to evaporate and that is what causes the odor. This process may take up to 2 weeks, depending on the number and location of the dead mice. I the winter, with cooler temperatures, less wall void insects, and lower vapor pressure, this timeline may be extended. Once the population is knocked down, exclusion may proceed. A thorough job will not only protect your home, but will lessen the need for baits, and keep mice outside where they should be.

Outside the home there are things that may decrease the amount of mice running around. Lifting wood piles, sealing sheds, reducing cover near the house, and moving yard debris away from the house will all remove harborage and natural shelter from predators such as weasels, cats, owls, hawks, and coyotes. With this in mind, we take an Integrated Pest Management approach. After a thorough inspection of your home and surrounding property, a Pest Control Professional will be able to make specific recommendations regarding controlling mice. There is no need to live with mice!